1. Field of the Invention
This invention pertains generally to circuit interrupters and, more particularly, to medium voltage circuit breakers including a plurality of poles. The invention also relates to pole units for circuit interrupters. The invention further relates to pole unit conductor assemblies for pole units.
2. Background Information
Circuit interrupters provide protection for electrical systems from electrical fault conditions such as, for example, current overloads and short circuits. Various circuit interrupters include a spring powered operating mechanism, which opens electrical contacts to interrupt the current through the conductors of an electrical system in response to abnormal conditions, although a wide range of mechanical, electromechanical or other suitable driving mechanisms may be employed.
Vacuum circuit interrupters (e.g., vacuum circuit breakers; vacuum reclosers; other vacuum switching devices) include separable contacts disposed within an insulating housing. Vacuum circuit interrupters, such as, for example, power circuit breakers for systems operating above about 1,000 volts, typically utilize vacuum switches (not to be confused with vacuum switching devices), such as vacuum interrupters (not to be confused with vacuum circuit interrupters), as the switch element.
U.S. Pat. No. 5,912,604 discloses a recloser including a housing to which is attached a number of pole assemblies. A separate pole assembly is provided for each pole. Each pole assembly generally includes three subassemblies, namely a molded pole assembly, a connecting assembly and an actuator assembly. Protruding from each pole assembly are connection studs. The poles are molded from polyurethane, polymer concrete, epoxy or EPDM (ethylene propylene diene methylene). During a molding or casting operation, a vacuum interrupter and studs are placed in a mold and held in place by securing the studs. Any sensors, such as a current sensor and a voltage sensor, are held in place using porous insulating material. The current and voltage sensors are concentric rings positioned around a portion of one stud. The porous material is placed between the concentric rings and the stud. The polyurethane encapsulating material in its liquid state fills all mold voids including those voids in the porous insulating material.
It is known to provide circuit breaker pole assembly bottom conductors in the form of copper bars (or tubes) with an epoxy insulator on the outside. However, such known bottom conductors do not include any current transformer (CT) or any electronic sensing circuit. Since known CTs for corresponding circuit breakers are relatively very large and relatively very heavy, they are not disposed at the circuit breaker. Furthermore, such CTs would likely fail during circuit breaker testing.
There is room for improvement in medium voltage circuit interrupters.
There is also room for improvement in pole units for circuit interrupters.
There is further room for improvement in pole unit conductor assemblies for circuit interrupter pole units.